Nitrogen stress in crops has been measured for many years using inexpensive spectrometers with ranges up to 1000 nm. Detectors for spectral measurements above 1000 nm are expensive, but they can be used to analyze water stress in plants by measuring reflectance of the major water bands at 1450 nm and 1900 nm. Although there is a water band at 970 nm, it is generally considered to be too small and inconsistent to use as an indicator of water stress. This experiment aims to determine the correlation between reflectance at 970 nm and 1450 nm. This was done by taking single-leaf spectral measurements of excised soybean leaves over a two hour period. This data was then analyzed using three water stress indices and compared to the values at 1450 nm. Reflectance values at 970 nm were highly correlated with values at 1450 nm. The data indicate that water stress can be determined using the 970 water band.
Dallon, Daniel, "Measurement of Water Stress: Comparison of Reflectance at 970 and 1450 nm" (2003). Water Stress. Paper 1.